I should probably take a moment to point out that sparring isn’t play fighting or safe fighting, it’s a form of training. While you can spar without an instructor present, it isn’t actually overlooked until you get to the upper belt ranks and older teen/adult. While most sparring matches go fine, there are always a couple where someone (or everyone) screws up and the students get seriously injured. For example, my brother and a visiting black belt decided to put on the UFC fiberglass gloves (when they still made them) for our in-house tournament. Our instructors let them, and my brother got punched in the face. His eyesocket cracked, the muscles controlling the eye’s movement slipped down between the cracks. My mom was there and she rushed him to the hospital where he had to have surgery. If he hadn’t, he’d have lost the use of his eye.
That’s on the rarer side, but stuff like broken arms and legs happens. Are they all accidents? Yes. You can hurt someone else or injure them without any malicious intent meant. Training accidents happen to everyone, even to those who ostensibly know what they’re doing. Having your instructor or one of the black belts there when sparring means the greater chances that someone will be there if things do go wrong or be able to cut off tragedy at the pass before it has a chance to go over the edge.
Having someone even if it isn’t an instructor present when you spar is about safety. It is also about legality. While you do sign waivers when you join martial arts schools, the main point of a sparring activities is to ensure the proceedings are safe. The less padding, the greater the necessity for eyeballs. If you’re under black belt and a minor, then someone will probably be in the vicinity if these kids are sparring on premises even if there aren’t eyeballs directly on them at all times. And if they’re sparring when they shouldn’t? The first time they’ll get let off with a warning. If it becomes a repeat habit, they’ll get kicked out after they’re discovered.
There is a very distinct difference between “practicing your techniques with a partner” and “sparring”.
Practicing with a partner: you’re performing one technique or a combination of techniques in order to practice technique, precision, and learn distance with another human present to act as your dummy. This is not freestyle, it’s controlled. It goes back and forth. Practicing with a partner is very important for martial arts training because you’re figuring out new concepts you can’t get on your own such as the troublesome nature of finding pressure points, learning to adjust for another person’s weight, the actual length of your arms, etc. It is very controlled and it can be literally anything, from throwing roundhouse kicks back and forth to practicing your throws/grappling techniques. This is where most technical adjustments will happen.
Sparring: Sparring is a practice fight where you take everything you’ve learned and put it to the test against a live opponent in a mostly free-form format. The rules mostly change depending the martial art, on belt rank, or just for general safety (such as no blows to the head/no kicks to the head for minors). Sparring is not a substitute for a “real fight”, it’s just the closest you can get in a safe/controlled environment. People will take chances in sparring that they never would in real life simply because they know that it isn’t real or that they’re safe. If your characters aren’t practicing their techniques then no amount of sparring is going to help them improve. Doing a lot of sparring is like skipping ahead to F when you still need to work through A, B, C, D, and E. The boring stuff.
For example, most martial arts schools have one, yes only one, day of the week dedicated to sparring. It acts as a carrot to get kids interested in doing the boring stuff, much in the same way the prospect of dessert after the meal encourages children to eat their vegetables.
Just because your character is successful in sparring doesn’t mean they can do jack shit in a real fight. The closer their martial art hews in focus on street fighting/self-defense then the less freedom they’ll be allowed when sparring. You may be going “but it’s safe!”. It is never safe. Where two consenting adults can go at it legally, two minors will be in a host of trouble.
You need someone around who has some basic grasp of what they’re doing, free-form practicing rather than outright sparring is usually where innovation happens. If they don’t know enough to understand what it should look like, then the students will end up just baking their flaws into their techniques.
“I do not fear the man who has practiced 10,000 kicks once, but I fear the man who practiced one kick 10,000 times.” – Bruce Lee
This quote is pretty simple, but it trips people up. Bruce Lee is talking about refinement of the basics, which are the foundation of all martial arts. By focusing on a single technique, you carefully practice until it is perfect. Looking for flaws, adjusting yourself, fixing your mistakes, and continuing to work on it until it is the best it possibly can be. Whereas, the one who grabs at everything or doesn’t focus on their basics has no foundation and far less dangerous. This also directly applies to sparring because most students (not just writers) approach the exercise with the eagerness of “getting to do a real fight”.
If you assume your technique is fine or practice the same movement over and over again without thinking about it (as one might in sparring when their mind is on other things), then you eventually bake those flaws into your muscle memory. Once they end up in your muscles by the series of repetitions, they become much harder to extract.
It’s not that too much practice is bad or even that practice without oversight is bad, but rather practice without any thought, self-awareness, or critical analysis is what will catch you. When you find that balance of what the technique should look/feel like, you then practice it over and over repetitively until you can do it on command.
This is where techniques like the 1 hit KO roundhouse come from. One of the other masters in our organization shared a story about meeting my Master Gary Nakahama at a tournament. He and his friends were up in the stands laughing at this guy on the floor who was just practicing his roundhouse before the match over and over and over again. The match begins, KWJN Gary threw his roundhouse, hit his opponent in the head, and down the other man went. They all stopped laughing after that.
Lastly, it’s worth pointing out that while these two may be very good at fighting each other, if they only practice against one person then they will only be good against that person. One of the advantages of a class is that you get a wider sample size to practice with. People come in all different shapes and sizes with flaws and foibles, their bodies are all slightly different. Part of practicing with multiple individuals is learning to adjust on the fly to those changes.
All this is me saying that there isn’t anything wrong with your set up (other than the “we do real fighting but we don’t hurt people” which is a contradiction and still dumb), just giving you contextual information to think about surrounding these characters.
The other thing I would caution you to think long and hard about is the contradiction I mentioned above and why you want it. I’ve said it before but it bears repeating, there is no safety with violence. There’s only “as safe as we can make it”. Your martial art doesn’t make sense to me, except on the idea that it’s existing for narrative’s moral reasons. Your characters are going to have a difficult time sparring if they aren’t learning how to attack. At the very least step back and look at Aikido or some other martial arts that focus on a more non-violent approach.
Because it feels like you said, “roughly close to real violence except they don’t fight at all”. Most martial arts that hew toward “real life violence” don’t fuck around, they end it fast whether that’s a lightspeed throw that puts an opponent on their back or a headbutt to the face.
You might want to find some balance between your desire to have your characters be good at fighting but also whatever inner fear might linger that the reader won’t like them if they hurt people. Because right now it feels like they’ve been backed into a “martial art” that’s going to hamstring them.
That is just one person’s perspective, take what you will from it.